Incandescent cathode



Aug. 28, 1928. 1,682,642

B. VAN DER POL- INCANDESCENT GATHODE Filed May 11, 1925 I I I I I V I 1f x /5 IE/ L46 6/ w 7 r L 0 1 Patented Aug. 28, 1928.

UNITED STATES PATENT OFFICE.

BALTHAZAB VAN DER POL, OF EINDHOVEN, NETHERLANDS, ASSIGNOB TO N. V. PHILIPS GLOEILAMPENFABRIEKEN, 0F EINDHOVEN, NETHERLANDS.

INCANDESCENT CATHODE.

Application filed May 11, 1925, Serial No. 29,526, and in thefletherlands Kay 21, 1924.

This invention relates to incandescent cathodes for transmission tubes,which incandescent cathodes are heated by an electric current, moreparticularly to incandescent cathodes for transmission tubes ofcomparatively large outputs.

In transmission tubes for wireless telegraphy or telephony or inrectifiers, there are often used incandescent cathodes which havetheshape of a hair-pin. If the current in the filaments used for thispurpose becomes comparatively heavy, which is the casein transmissiontubes of large outputs, the electrodynamic forces acting on the parts ofthe filament increase to such a degree that these parts take othershapes under the influence of said forces; the two legs of ahairpin-shaped filament, for example, are bent outwards.

According to the invention, .in order to obviate said disadvantage theincandescent cathode consists of a number of substantially parallelparts, which are so arranged relatively to each other and to one or moreleading-in wires which are parallel to each other and to the parts ofthe filament, that the electrodynamic forces acting on the incandescentcathode substantially neutralize each other. i

According to the invention two parts of the filament and two leading-inwires may be arranged substantially parallel to each other so as to passthrough the angular points of such a rhombus that the distance betweenthe leading-in wires a r ranged diagonally opposite each other is 3times the distance bet-ween the parts of the filament. The four elementsare further so arranged that the electric currents havesubstantially-the same value and that'the direction of the currentspassing through the two parts of the filament is the same, but isopposite to the direction of the currents traversing the leading-inwires.

The accompanying drawings illustrate by way of example some embodimentsof the invention. In the said drawingfl Figure 1 shows a construction ofan incandescent cathode in which two parts of the filament and twoleading-in, wires are arranged parallel to each other.

Figure 2 is a plan of the incandescent cathode with its support as shownin Figure 1.

Figure 3 is a sectional view of a rectifier arrows) comprising anincandescentcathode accordto Figure 1. f

According to Figure 1 the support of the incandescent cathode consistsof a metal clip 1, which has two parallel parts 3 and 4 and is carriedby a conductor 2. To the upper connecting piece of the clip a metal rod5 is secured which carries parts 6 and 7 of a filament which aresuspended so as to be, parallel to each other and to the leading-inwires 3 and 4. The other ends of'these filaments are secured to a clip 8which is carried by a conductor 95 It is clear from the drawing that thecurrents passing through the wires 3 and 4 have the same direction, buthave an opposite direction compared with the currents traversing thewires 6 and 7 (see the The distance between the wires 3 and 4 must beabout 3 times the distance between the filaments 6 and 7.

The electric discharge tube shown in Figure 3, which may serve torectify alternating.

currents, is provided with an incandescent cathode of the sameconstruction as is shown in Figures 1 and 2. The conductors 2 and 9 aresecured to metal hoods 10 and 11 which at their edges are hermeticallysealed to glass tubes 12 and 13, which again archermetically sealed to aglass vessel 16. On their other sides the metal hoods 10 and 11 carryleading-in wires 14 and 15. A metalvessel 17 which serves as anode isheremetically sealed to the end of a glass vessel 16.

What I claim is r 1. A cathode for a discharge tube comprising a pair ofparallel lead-inwires, a' pair of parallel filament wires parallel tothe said lead-in wires and connections so that the current in each pairof wires is in the-same direction.

2. A cathode for a discharge tube comprising a pair of parallel lead-1nwires, and lead-in wires also serving asa filament support, a pair ofparallel filament wires, and connections so that the current in eachpair of wires is in the same direction.

3. A cathode for a discharge tube comprising a support substantiallyrectangular in shape and of conducting material, a leadin connection tosaid support, a cross bar.

secured to said support, parallel filaments of parallel filamentsparallel to said arms,

and an electrical connection between one end of the parallelarms and theadjacent end of the filaments adapted to cause the current to flow inopposite directions in the lead-in arms relatively to the' current inthe filaments. 1

5. A cathode for discharge tubes compris in a lead-in wire forming aloop with parthe arms being adapted tosupport a filament, said filamentsbein arallel to each other and to the arms, and t e opposite end of thefilaments being electrically connected to a second lead-in wire.

7. A cathode for discharge tubes comprising a plurality of conductorseach adapted to carry equal amounts of current in the same direction, alead-in connection to one end of said conductors, and a plurality offilaments one end of which is connected to the other ends of theconductors and adapted to carry equal amounts of current in the samedirection, and the other end of the filaments connected to a secondlead-in wire.

In testimony whereof I affix my signature, at the city of Eindhoven,this seventeeth day of April, A. D. 1925.

BALTHAZAR VAN DER POL.

